Conventionally, as a wire electric discharge machining method, there is proposed a discharge wire-saw method in which, when a thin plate is sliced from a workpiece having a columnar shape, a wire electrode is wound between a plurality of guide rollers and arranged in parallel to form multiple cut wire portions, power is fed individually to each cut wire portion so that electric discharge occurs between each cut wire portion and the workpiece, thereby cutting the workpiece into a plurality of pieces at a time.
In the discharge wire-saw having the configuration described above, retaining means for reliably retaining the workpiece is required to perform machining stably. For example, Patent Literature 1 discloses a technique in which a conductive fixing base extending in an axial direction is prepared in a part of a columnar workpiece in a circumferential direction, and the fixing base and the workpiece are fixed by an adhesive having electrical conductivity, that is, a technique for retaining the workpiece by the fixing base.
Furthermore, Patent Literature 2 discloses a technique in which, in a multi wire-saw that supplies a machining fluid including abrasive grains to a portion between a wire and a workpiece and cuts multiple wafers by an abrasive action, while pressing the workpiece against a plurality of wire lines, a workpiece is mounted on a dummy member having an L-shaped cross section, and cutting is performed together with the dummy member, while supporting a grinding resistance acting on a portion to be cut by a side portion of the dummy member. Patent Literature 2 describes that setting of the workpiece and removal of the workpiece after cutting are efficiently performed according to this method.
Further, Patent Literature 3 discloses a technique in which, when different materials of a workpiece having a composite structure manufactured by combining different materials having a difference in hardness are simultaneously cut or ground, an inside edge of a material to be cut having high hardness or brittleness is chamfered in advance to generate a groove in an interface with another material, thereby performing simultaneous-cutting, cutting, or grinding highly accurately without damaging a blade.